Hi, thanks for posting your Question..
At times you may experience Problems with a Garmin Astro DC30 Collar. I've heard And experienced reports of the following problems with Garmin DC 30 Collars
Before trying to do a Hard Reset for the Garmin Astro 220 DC30 Collar you should try and identify if it is the collar or the 220 Receiver. the easiest way you can do this is to check your Tracking System with another collar. If the second collar works fine then you can assume that you DC30 is not working as it should.
First i would Check all the basics, make sure the collar is charged.
I also would Delete and Re establish the Dog Collar in you system by going to the Dog List on the menu of the Astro 200, I would probably recommend Resetting the 220 receiver since it is much easier to reset that than the Collar.
Lastly, If these do not fix your problem you should try to "reset" the DC30 by
Removing the Back Plate (silver piece)
While Your looking at the connections for the two antennas, I would check to make sure there is nothing wrong with both the GPS antenna connection, and the VHF Antenna on the collar. Personally I carefully disconnect each and make sure they are both clean and free of Debris and Junk. (good Solid connection here will only help the performance of the collar) You can carefully use a brush or electronics contact cleaner for the VHF antenna (Screw mount) (See images below). I would not put anything into the SMP (square Antenna wire connector)
Removing the VHF Antenna on a DC30
Clean this before re-installing. Very Important to have a good Electrical connection3. Remove the Four Small Philips screws on the outside of the case to access the battery and electronics compartment. Very Carefully Disconnect the white battery connector from the board (see images below). Leave the battery Disconnected for about 15-20 minutes for a full reset, Reconnect it to the board.. (CAREFULLY) Here you Can see the battery Connector for the DC 30 Garmin
Different Angle of the connector for Dc30
As you re-assemble the Garmin DC30, Clean all seals and clean antenna connections.
Clean all seals and connections before re-assebling the Garmin DC30 collar
That is A Garmin DC30 Reset Instructions, and Many times when you are having Problems with Garmin DC30 collars this is the First step Garmin will ask you to do before sending them back.
Here is how to Mark a Location other than your location. For example You might want to mark the Tree before you get to it in case your dogs leave the tree. Most of the time If you are like myself You want to Scroll over and Hit the Mark Button, However that will just Mark Your current Location and not the location that your cursor is.
Here are the instructions To mark a location where your cursor is on your Astro 220.
Scroll the cursor over to the location you want to mark.
Press (ENTER) instead of pressing Mark.
If you press Mark it will mark your current location..
After you press enter.
It will either Select something that you've scrolled over and you should be able to save that as a Location, (Hint: you can change the name to what ever you want before you save it.)
Or if it doesn't select something it will say "no Map info at this point. Do You want to Mark a location here"
I know it's pretty confusing and counter intuitive, But that's how you can mark a location where you are not at.
If your Antenna's are not too OK,you can get a replacement from the below link:http://garminastrodog.com/garmin-astro-dog-tracking-antenna-questions/
Good luck and thanks for using fixya.